Voltage-dependent non-linear resistance ceramic composition

ABSTRACT

A voltage-dependent non-linear resistance ceramic composition comprises SrTiO 3 , Sr 1-x  Ba x  TiO 3  (0.001≦x≦0.300) or Sr 1-x  Ca x  TiO 3  (0.001≦x≦0.300) as host material and further includes 0.001-2.000 mol % of Y 2  O 3  as metal oxide for semiconductorization acceleration, 0.001-3.000 mol % of metal oxide(s) of at least one selected from the group consisting of Ca 2  O 3 , CuO, Ag 2  O, Al 2  O 3 , ZrO 2 , Bao, SiO 2 , MgO, B 2  O 3 , MnO 2 , NiO, MoO 3  BeO, Fe 2  O 3 , Li 2  O, Cr 2  O 3 , PbO, CaO, TiO 2 , P 2  O 5 , Sb 2  O 3  and V 2  O 5 , which segregates at grain boundary to make the grain boundary selectively to high resistances; an element made of the composition has both characteristics of capacitance and varistor, and is suitable for filter to remove noise or surge.

This is a continuation of application Ser. No. 715,945 filed Mar. 25, 1985 which was abandoned upon the filing hereof.

DESCRIPTION

1. Technical Field

The present invention relates to a voltage dependent non-linear resistance ceramic composition for use in surge absorbing, noise elimination and a measure against undesirable electric changing in various electric apparatuses and electronic apparatuses.

2. Background Art

Heretofore, in various electric apparatuses and electronic apparatuses, in order to absorb extraordinary high voltage, elimination of noise, elimination of arc, and the like, SiC baristors or varistors of ZnO system having a voltage-dependent non-linear resistance characteristics are used. Voltage-current characteristic of such baristors can be approximately represented by the following equation:

    I=(V/C).sup.α,

wherein I is current, V is voltage, C is a constant proper for the baristor, and α is a voltage non-linearity exponent.

The α of the SiC baristor is about 2-7, and for the ZnO system baristor there is ones that reaching 50. Though such baristors has superior characteristic for absorbing relatively high voltage called surge, for voltages lower than baristor voltage (for instance, absorption of noise) almost no effect is represented since its dielectric constant is low and its inherent capacitance is small, and their dielectric loss tan δ are so large as 5-10%.

On the other hand, for elimination of low voltage noise, static electricity, or the like, by appropriately selecting composition and firing condition, semiconductor ceramic capacitors having apparent dielectric constant of about 5×10⁴ -6×10⁴ and tan δ of about 1% are utilized.

However, these semiconductor ceramic capacitor is liable to be destroyed or become to be non-functional as capacitors when extraordinary high voltage such as surge is impressed thereon or a current above a certain limit is impressed on the element. For such reason, in the electric apparatuses or electronic apparatuses, for the purpose of both the absorbing of high voltage surge and the elimination of low voltage noise, the baristors are used being combined with capacitors and other component (for instance, coil), and for instance, a noise filter has such configuration.

FIG. 1 shows general noise filter circuit, FIG. 2 shows conventional noise filter circuit constituted by combining a baristor, capacitors and a coil, and 1 is the coil, 2 are the capacitors and 3 is the baristor.

When a noise input A shown in FIG. 5 is impressed on these circuits, output characteristic from general noise filter circuit of FIG. 1 is such as C of FIG. 5, and noise is not eliminated sufficiently. Output characteristic from the conventional noise filter circuit including a baristor shown in FIG. 2 is such as B of FIG. 5, and though noise is eliminated, such configuration has a shortcoming that it has large number of components in the inside of the apparatus and besides is contrary to tendency of miniaturization of the apparatus.

Accordingly, an electronic component, which absorbs extrraordinary high voltage, can eliminate low voltage, such as noise and has small number of components, and capable of miniaturization, is demanded.

SUMMARY OF THE INVENTION

Accordingly, the present invention intends to provide a voltage-dependent non-linear resistance ceramic composition comprising SrTiO₃, Sr_(1-x) Ba_(x) TiO₃ (0.001≦x≦0.300) or Sr_(1-x) Ca_(x) TiO₃ (0.001≦x≦0.300) as host material, including 0.001-2.000 mol % of Y₂ O₃ as metal oxide for semiconductorization acceleration, and including 0.001-3.000 mol % of oxide(s) of at least one metal selected from the group consisting of Co₂ O₃, CuO, Ag₂ O, Al₂ O₃, ZrO₂, BaO, SiO₂, MgO, B₂ O₃, MnO₂, NiO, MoO₃, BeO, Fe₂ O₃, Li₂ O, Cr₂ O₃, PbO, CaO, TiO₂, P₂ O₅, Sb₂ O₃ and V₂ O₅, which segregates at grain boundary to make the grain boundary to high resistance.

BRIEF EXPLANATION OF THE DRAWING

FIG. 1 is a circuit diagram of a general noise filter.

FIG. 2 is a circuit diagram of a noise filter using the conventional varistors and the capacitors.

FIG. 3 is a sectional view of an element using voltage dependent non-linear resistance ceramic composition in accordance with the present invention.

FIG. 4 is a circuit diagram of a noise filter using the voltage dependent non-linear resistance ceramic composition in accordance with the present invention.

FIG. 5 is a characteristic chart showing situation of input noise and output in accordance with circuit of noise filters of the present invention and the prior art.

FIG. 6 is a characteristic diagram showing relation between Sr/Ti ratio and specific resistance.

FIG. 7 is a characteristic diagram showing relation between Sr/Ti ratio and tan δ.

THE BEST MODE FOR EMBODYING THE INVENTION

As a result of accumulation of various experiments, the inventors made a voltage dependent non-linear resistance ceramic composition in a quite different system from the conventional composition by making SrTiO₃, Sr_(1-x) Ba_(x) TiO₃ (0.001≦x≦0.300) or Sr_(1-x) Ca_(x) TiO₃ (0.001≦x≦0.300) as host material, and Y₂ O₃ as semiconductorization accelerating agent, and by further adding Co₂ O₃ and CuO, and further adding if necessary an appropriate amount of additive. Hereafter, the present invention is described with respect to embodiments, with reference to the accompanying drawings.

<EXAMPLE 1>

After measuring SrCO₃ and TiO₂ in a manner that SrTiO₃ having Sr/Ti atom ratio of 0.98 is obtained, and they are blended for 15 hours in wet method in a ball-mill or the like. And after driving the mixture is then dried, and then is grounded. Thereafter the grounded powder is calcinated for 3 hours at 1100° C. in the air and again grounded to produce SrTiO₃ powder.

Next, SrTiO₃, Y₂ O₃, Co₂ O₃, CuO, Ag₂ O and Al₂ O₃ are measured and blended in an ingredient component as shown in the following Table 1.

                                      TABLE 1                                      __________________________________________________________________________     Composition ratio                                                                  First    Second Third   Fourth Fifth                                       Sample                                                                             component                                                                               component                                                                             component                                                                              component                                                                             component                                   No. SrTiO.sub.3 (mol %)                                                                     Y.sub.2 O.sub.3 (mol %)                                                               Co.sub.2 O.sub.3 (mol %)                                                               CuO (mol %)                                                                           Additive                                                                            mol %                                  __________________________________________________________________________      1* 99.999   0.001  0.000   0.000  --   0.000                                   2* 99.900   0.100  0.000   0.000  --   0.000                                   3* 99.000   1.000  0.000   0.000  --   0.000                                   4* 98.000   2.000  0.000   0.000  --   0.000                                   5* 97.000   3.000  0.000   0.000  --   0.000                                   6* 99.998   0.001  0.001   0.000  --   0.000                                   7  99.889   0.100  0.010   0.001  --   0.000                                   8  99.199   0.300  0.500   0.001  --   0.000                                   9  97.999   1.000  1.000   0.001  --   0.000                                  10  96.499   1.500  2.000   0.001  --   0.000                                   11*                                                                               95.499   1.500  3.000   0.001  --   0.000                                  12  99.988   0.001  0.001   0.010  --   0.000                                  13  99.889   0.010  0.001   0.100  --   0.000                                  14  99.489   0.010  0.001   0.500  --   0.000                                  15  97.999   1.000  0.001   1.000  --   0.000                                   16*                                                                               96.999   1.000  0.001   2.000  --   0.000                                  17  99.700   0.100  0.100   0.100  --   0.000                                  18  99.300   0.100  0.300   0.300  --   0.000                                  19  98.600   0.100  0.300   1.000  --   0.000                                  20  98.600   0.100  1.000   0.300  --   0.000                                  21  97.700   0.300  1.500   0.500  --   0.000                                  22  97.200   1.000  1.000   0.800  --   0.000                                  23  96.000   2.000  1.000   1.000  --   0.000                                  24  99.699   0.100  0.100   0.100  Ag.sub.2 O                                                                          0.001                                  25  99.699   0.100  0.100   0.100  Al.sub.2 O.sub.3                                                                    0.001                                  26  99.490   0.100  0.300   0.100  Ag.sub.2 O                                                                          0.010                                  27  99.200   0.100  0.300   0.100  Al.sub.2 O.sub.3                                                                    0.300                                  28  98.250   0.300  0.300   0.150  Ag.sub.2 O                                                                          1.000                                  29  97.150   0.500  0.300   0.050  Al.sub.2 O.sub.3                                                                    2.000                                  30  95.900   0.500  0.500   0.100  Al.sub.2 O.sub.3                                                                    3.000                                   31*                                                                               94.950   0.800  0.700   0.050  Ag.sub.2 O                                                                          3.500                                  32  99.699   0.100  0.100   0.050  Ag.sub.2 O                                                                          0.001                                                                     Al.sub.2 O.sub.3                                                                    0.050                                  33  99.240   0.100  0.100   0.050  Ag.sub.2 O                                                                          0.010                                                                     Al.sub.2 O.sub.3                                                                    0.500                                  34  98.650   0.100  0.100   0.050  Ag.sub.2 O                                                                          0.100                                                                     Al.sub.2 O.sub.3                                                                    1.000                                  35  97.350   0.300  0.200   0.100  Ag.sub.2 O                                                                          0.050                                                                     Al.sub.2 O.sub.3                                                                    2.000                                  36  96.840   0.300  0.300   0.050  Ag.sub.2 O                                                                          0.010                                                                     Al.sub.2 O.sub.3                                                                    2.500                                   37*                                                                               95.800   0.500  0.200   0.100  Ag.sub.2 O                                                                          0.200                                                                     Al.sub.2 O.sub.3                                                                    3.200                                  __________________________________________________________________________      Marked * are comparison examples which are outside the claimed scope.    

Further, the mixture is blended in a ball mill for 20 hours, dried and then grounded. And subsequently, by adding 10-15 weight % of organic binder such as polyvinylalchohol the powder is granulated, and formed in a shape and size of 10 mm diameter and 1 mm thick disk by application of a pressing force of about 1.0 t/cm².

Then, the press-formed disk is fired for 4 hours at a temperature of 1380° C. in a reducing atmosphere of N₂ (90% in volume)+H₂ (10% in volume). It is further heat treated at 1100° C. for 4 hours in the air. The disk shaped sintered body 1 shown in FIG. 1 obtained in the above-mentioned process has almost the same component ratio as that of the starting materials.

On both faces of the sintered body 1, electrodes 2 and 3 are formed by applying conductive paint containing silver powder or the like and subsequently burning it.

Characteristics of the element obtained in the above-mentioned manner is shown in Table 2.

                  TABLE 2                                                          ______________________________________                                         Sample                                                                         No.   V.sub.1 mA /.sub.mm (V)                                                                     α ε                                                                              tan · δ (%)                  ______________________________________                                          1*   83.0         1.3     1.0 × 10.sup.6                                                                   94.0                                         2*   85.5         1.9     1.4 × 10.sup.6                                                                   91.2                                         3*   82.0         2.8     1.2 × 10.sup.6                                                                   87.1                                         4*   94.0         3.5     7.6 × 10.sup.5                                                                   77.0                                         5*   103.7        4.4     3.2 × 10.sup.5                                                                   70.8                                         6*   50.6         6.0     1.9 × 10.sup.4                                                                   6.4                                          7    37.3         7.9     3.2 × 10.sup.4                                                                   3.8                                          8    33.8         8.0     3.9 × 10.sup.4                                                                   3.1                                          9    31.7         8.6     4.5 × 10.sup.4                                                                   3.0                                         10    35.4         8.1     5.2 × 10.sup.4                                                                   3.1                                          11*  55.1         7.2     9.4 × 10.sup.4                                                                   6.0                                         12    42.5         8.2     4.9 × 10.sup.4                                                                   4.0                                         13    43.8         8.9     5.8 × 10.sup.4                                                                   3.8                                         14    58.2         9.2     4.0 × 10.sup.4                                                                   3.5                                         15    70.4         10.3    3.3 × 10.sup.4                                                                   3.1                                          16*  210.3        10.0    3.1 × 10.sup.3                                                                   1.4                                         17    35.2         8.0     5.2 × 10.sup.4                                                                   3.5                                         18    30.7         8.7     5.6 ×  10.sup.4                                                                  3.4                                         19    47.1         9.3     5.0 × 10.sup.4                                                                   3.0                                         20    43.3         9.5     4.7 × 10.sup.4                                                                   3.1                                         21    39.9         9.7     4.6 × 10.sup.4                                                                   3.0                                         22    37.8         10.2    4.8 × 10.sup.4                                                                   3.0                                         23    41.0         10.5    4.4 × 10.sup.4                                                                   3.0                                         24    42.3         9.3     6.1 × 10.sup.4                                                                   2.4                                         25    40.7         8.7     5.2 × 10.sup.4                                                                   3.3                                         26    44.4         9.9     6.3 × 10.sup.4                                                                   2.2                                         27    42.3         9.1     5.0 × 10.sup.4                                                                   3.1                                         28    57.2         10.7    4.1 × 10.sup.4                                                                   1.9                                         29    48.1         10.0    4.2 × 10.sup.4                                                                   3.0                                         30    50.3         9.8     3.9 × 10.sup.4                                                                   2.9                                          31*  319.6        10.1    4.2 × 10.sup.3                                                                   1.5                                         32    39.9         9.4     6.9 × 10.sup.4                                                                   1.9                                         33    44.3         9.9     6.2 × 10.sup.4                                                                   1.8                                         34    49.7         10.2    4.9 × 10.sup.4                                                                   1.7                                         35    50.8         10.4    4.3 × 10.sup.4                                                                   1.6                                         36    61.3         10.8    4.0 × 10.sup.4                                                                   1.6                                          37*  104.0        9.3     5.1 × 10.sup.3                                                                   3.9                                         ______________________________________                                          Marked * are comparison examples which are outside the claimed scope.    

Herein, assessment of characteristics of the elements as varistor can be made by α and C in a voltage-current characteristic equation:

    I=(V/C).sup.α

wherein I is current, V is voltage, C is a constant proper to the varistor and α is a non-linearity exponent. In the present invention, since accurate measurement of C is difficult, characteristic assessment as varistor is made by the value of varistor voltage for unit thickness when 1 mA of varistor current is made to flow (hereinafter such varister voltage is called as V₁ mA/mm), and by the value of α=1/log (V₁₀ mA/V₁ mA), wherein V₁₀ mA is a varistor voltage when a varistor current of 10 mA is flowed and V₁ mA is a varistor voltage when varistor current of 1 mA is flowed.

And characteristic assessment as the capacitors are made by a dielectric constant ε and dielectric loss tan δ at a measurement frequency of 1 KHz.

<EXAMPLE 2>

SrCO₃, BaCO₃ and TiO₂ are measured and blended in a manner to make Sr₀.9 Ba₀.1 TiO₃, and blended and grounded in a ball mill in a wet method for 15 hours. And the mixture is dried and ground, and then fired at 1200° C. for 3 hours, and further grounded thereby to prepare powder of Sr₀.9 Ba₀.1 TiO₃. Then, Y₂ O₃, Co₂ O₃, CuO, Ag₂ O and Al₂ O₃ are measured added to the above-mentioned powder of Sr₀.9 Ba₀.1 TiO₃, in a manner to make the composition ratio shown Table 3.

                                      TABLE 3                                      __________________________________________________________________________     Composition ratio                                                                  First                                                                      component                                                                          Second  Third  Fourth  Fifth                                               Sample                                                                             Sr.sub.0.9 Ba.sub.0.1 TiO.sub.3                                                        component                                                                             component                                                                              component                                                                             component                                    No. (mol %) Y.sub.2 O.sub.3 (mol %)                                                               Co.sub.2 O.sub.3 (mol %)                                                               CuO (mol %)                                                                           Additive                                                                            mol %                                   __________________________________________________________________________      1* 99.999  0.001  0       0      --   --                                       2* 99.900  0.100  0       0      --   --                                       3* 99.000  1.000  0       0      --   --                                       4* 98.000  2.000  0       0      --   --                                       5* 97.000  3.000  0       0      --   --                                       6* 99.998  0.001  0.001   0      --   --                                       7  99.889  0.100  0.010   0.001  --   --                                       8  99.199  0.300  0.500   0.001  --   --                                       9  97.999  1.000  1.000   0.001  --   --                                      10  96.499  1.500  2.000   0.001  --   --                                       11*                                                                               95.499  1.500  3.000   0.001  --   --                                      12  99.988  0.001  0.001   0.001  --   --                                      13  99.889  0.010  0.001   0.100  --   --                                      14  99.489  0.010  0.001   0.500  --   --                                      15  97.999  1.000  0.001   1.000  --   --                                       16*                                                                               96.999  1.000  0.001   2.000  --   --                                      17  99.700  0.100  0.100   0.100  --   --                                      18  99.300  0.100  0.300   0.300  --   --                                      19  98.600  0.100  0.300   1.000  --   --                                      20  98.600  0.100  1.000   0.300  --   --                                      21  97.700  0.300  1.500   0.500  --   --                                      22  97.200  1.000  1.000   0.800  --   --                                      23  96.000  2.000  1.000   1.000  --   --                                      24  99.699  0.100  0.100   0.100  Ag.sub.2 O                                                                          0.001                                   25  99.699  0.100  0.100   0.100  Al.sub.2 O.sub.3                                                                    0.001                                   26  99.490  0.100  0.300   0.100  Ag.sub.2 O                                                                          0.010                                   27  99.200  0.100  0.300   0.100  Al.sub.2 O.sub.3                                                                    0.300                                   28  98.250  0.300  0.300   0.150  Ag.sub.2 O                                                                          1.000                                   29  97.150  0.500  0.300   0.050  Al.sub.2 O.sub.3                                                                    2.000                                   30  95.900  0.500  0.500   0.100  Al.sub.2 O.sub.3                                                                    3.000                                    31*                                                                               94.950  0.800  0.700   0.050  Ag.sub.2 O                                                                          3.500                                   32  99.699  0.100  0.100   0.050  Ag.sub.2 O                                                                          0.001                                                                     Al.sub.2 O.sub.3                                                                    0.050                                   33  99.240  0.100  0.100   0.050  Ag.sub.2 O                                                                          0.010                                                                     Al.sub.2 O.sub.3                                                                    0.500                                   34  98.650  0.100  0.100   0.050  Ag.sub. 2 O                                                                         0.100                                                                     Al.sub.2 O.sub.3                                                                    1.000                                   35  97.350  0.300  0.200   0.100  Ag.sub.2 O                                                                          0.050                                                                     Al.sub.2 O.sub.3                                                                    2.000                                   36  96.840  0.300  0.300   0.050  Ag.sub.2 O                                                                          0.010                                                                     Al.sub.2 O.sub.3                                                                    2.500                                    37*                                                                               95.800  0.500  0.200   0.100  Ag.sub.2 O                                                                          0.200                                                                     Al.sub.2 O.sub.3                                                                    3.200                                   __________________________________________________________________________      Marked * are comparison examples which are outside the claimed scope.    

The above-mentioned starting material is mixed, press-formed and fired in the same condition way and conditions as of EXAMPLE 1 to make the similar element as that of EXAMPLE 1. The characteristics of the element are measured in the same way as that of EXAMPLE 1, and the measured results are shown in Table 4.

                  TABLE 4                                                          ______________________________________                                         Sample                                                                         No.     V.sub.1mA /.sub.mm (V)                                                                     α  ε                                                                             tan δ (%)                            ______________________________________                                          1*     85.0        1.3      1.0 × 10.sup.6                                                                  90.9                                        2*     86.9        1.8      1.4 × 10.sup.6                                                                  84.5                                        3*     84.5        2.0      1.2 × 10.sup.6                                                                  82.0                                        4*     103.0       2.9      7.5 × 10.sup.5                                                                  80.0                                        5*     112.1       3.8      1.0 × 10.sup.5                                                                  71.8                                        6*     57.4        4.7      1.6 × 10.sup.4                                                                  9.2                                         7      38.2        7.2      3.3 × 10.sup.4                                                                  3.9                                         8      36.3        7.3      3.8 × 10.sup.4                                                                  3.3                                         9      33.8        7.8      4.5 × 10.sup.4                                                                  3.2                                        10      37.7        8.0      4.8 × 10.sup.4                                                                  3.1                                         11*    61.9        5.7      7.0 × 10.sup.4                                                                  10.0                                       12      44.4        7.7      4.5 × 10.sup.4                                                                  3.9                                        13      45.7        7.9      5.0 × 10.sup.4                                                                  3.8                                        14      60.4        8.1      4.3 × 10.sup.4                                                                  3.7                                        15      71.3        9.2      3.9 × 10.sup.4                                                                  3.2                                         16*    235.3       8.1      2.8 × 10.sup.3                                                                  1.9                                        17      39.1        7.2      4.8 × 10.sup.4                                                                  3.4                                        18      32.9        7.5      5.0 × 10.sup.4                                                                  3.4                                        19      49.8        7.9      5.2 × 10.sup.4                                                                  3.3                                        20      40.8        8.8      4.7 × 10.sup.4                                                                  3.0                                        21      38.3        8.8      4.6 × 10.sup.4                                                                  3.0                                        22      33.5        8.9      4.4 × 10.sup.4                                                                  3.0                                        23      39.9        9.1      4.0 × 10.sup.4                                                                  3.0                                        24      43.5        9.2      5.3 × 10.sup.4                                                                  2.5                                        25      44.6        8.7      4.8 × 10.sup.4                                                                  3.2                                        26      59.8        9.7      5.1 × 10.sup.4                                                                  2.4                                        27      48.7        9.0      4.7 × 10.sup.4                                                                  3.2                                        28      61.8        10.5     4.0 × 10.sup.4                                                                  2.4                                        29      50.3        9.5      4.0 × 10.sup.4                                                                  3.5                                        30      52.1        9.7      2.1 × 10.sup.4                                                                  3.1                                         31*    309.0       9.9      3.3 × 10.sup.3                                                                  1.9                                        32      42.5        9.5      5.7 × 10.sup.4                                                                  1.9                                        33      48.1        9.7      5.5 × 10.sup.4                                                                  1.8                                        34      52.0        9.9      3.1 × 10.sup.4                                                                  1.8                                        35      54.8        10.0     3.3 × 10.sup.4                                                                  1.9                                        36      63.7        10.3     3.9 × 10.sup.4                                                                  2.3                                         37*    114.0       9.1      2.1 × 10.sup.3                                                                  5.0                                        ______________________________________                                    

<EXAMPLE 3>

SrCO₃, CaCO₃ and TiO₂ are measured and blended in a manner to make Sr₀.9 Ca₀.1 TiO₃, and blended and grounded in a ball mill in a wet method for 15 hours. And the mixture is dried and ground, and then fired at 1200° C. for 3 hours, and further grounded thereby to prepare powder of Sr₀.9 Ca₀.1 TiO₃. Then, Y₂ O₃, Co₂ O₃, CuO, Ag₂ O and Al₂ O₃ are measured added to the above-mentioned powder of Sr₀.9 Ca₀.1 TiO₃, in a manner to make the composition ratio shown Table 5.

                                      TABLE 5                                      __________________________________________________________________________     Composition ratio                                                                  First       Second  Third   Fourth Fifth                                   Sample                                                                             component   component                                                                              component                                                                              component                                                                             component                               No. Sr.sub.0.9 Ca.sub.0.1 TiO.sub.3 (mol %)                                                    Y.sub.2 O.sub.3 (mol %)                                                                Co.sub.2 O.sub.3 (mol %)                                                               CuO (mol %)                                                                           Additive                                                                            mol %                              __________________________________________________________________________      1* 99.999      0.001   0       0      --   --                                  2* 99.900      0.100   0       0      --   --                                  3* 99.000      1.000   0       0      --   --                                  4* 98.000      2.000   0       0      --   --                                  5* 97.000      3.000   0       0      --   --                                  6* 99.998      0.001   0.001   0      --   --                                  7  99.889      0.100   0.010   0.001  --   --                                  8  99.199      0.300   0.500   0.001  --   --                                  9  97.999      1.000   1.000   0.001  --   --                                 10  96.499      1.500   2.000   0.001  --   --                                  11*                                                                               95.499      1.500   3.000   0.001  --   --                                 12  99.988      0.001   0.001   0.001  --   --                                 13  99.889      0.010   0.001   0.100  --   --                                 14  99.489      0.010   0.001   0.500  --   --                                 15  97.999      1.000   0.001   1.000  --   --                                  16*                                                                               96.999      1.000   0.001   2.000  --   --                                 17  99.700      0.100   0.100   0.100  --   --                                 18  99.300      0.100   0.300   0.300  --   --                                 19  98.600      0.100   0.300   1.000  --   --                                 20  98.600      0.100   1.000   0.300  --   --                                 21  97.700      0.300   1.500   0.500  --   --                                 22  97.200      1.000   1.000   0.800  --   --                                 23  96.000      2.000   1.000   1.000  --   --                                 24  99.699      0.100   0.100   0.100  Ag.sub.2 O                                                                          0.001                              25  99.699      0.100   0.100   0.100  Al.sub.2 O.sub.3                                                                    0.001                              26  99.490      0.100   0.300   0.100  Ag.sub.2 O                                                                          0.010                              27  99.200      0.100   0.300   0.100  Al.sub.2 O.sub.3                                                                    0.300                              28  98.250      0.300   0.300   0.150  Ag.sub.2 O                                                                          1.000                              29  97.150      0.500   0.300   0.050  Al.sub.2 O.sub.3                                                                    2.000                              30  95.900      0.500   0.500   0.100  Al.sub.2 O.sub.3                                                                    3.000                               31*                                                                               94.950      0.800   0.700   0.050  Ag.sub.2 O                                                                          3.500                              32  99.699      0.100   0.100   0.050  Ag.sub.2 O                                                                          0.001                                                                     Al.sub.2 O.sub.3                                                                    0.050                              33  99.240      0.100   0.100   0.050  Ag.sub.2 O                                                                          0.010                                                                     Al.sub. 2 O.sub.3                                                                   0.500                              34  98.650      0.100   0.100   0.050  Ag.sub.2 O                                                                          0.100                                                                     Al.sub.2 O.sub.3                                                                    1.000                              35  97.350      0.300   0.200   0.100  Ag.sub.2 O                                                                          0.050                                                                     Al.sub.2 O.sub.3                                                                    2.000                              36  96.840      0.300   0.300   0.050  Ag.sub.2 O                                                                          0.010                                                                     Al.sub.2 O.sub.3                                                                    2.500                               37*                                                                               95.800      0.500   0.200   0.100  Ag.sub.2 O                                                                          0.200                                                                     Al.sub.2 O.sub.3                                                                    3.200                              __________________________________________________________________________      Marked * are comparison examples which are outside the claimed scope.    

The above-mentioned starting material is mixed, press-formed and fired in the same condition way and conditions as of EXAMPLE 1 to make the similar element as that of EXAMPLE 1. The characteristics of the element are measured in the same way as that of EXAMPLE 1, and the measured results are shown in Table 6.

                  TABLE 6                                                          ______________________________________                                         Sample                                                                         No.     V1mA/mm(V)  α  ε                                                                             tan δ (%)                            ______________________________________                                          1*     82.0        1.3      1.1 × 10.sup.6                                                                  99.0                                        2*     85.0        1.8      1.5 × 10.sup.6                                                                  92.4                                        3*     80.1        2.4      1.3 × 10.sup.6                                                                  90.1                                        4*     92.0        3.0      7.7 × 10.sup.5                                                                  85.7                                        5*     100.3       4.1      1.3 × 10.sup.5                                                                  88.1                                        6*     46.5        5.3      1.7 × 10.sup.4                                                                  8.1                                        7       33.6        7.6      3.4 × 10.sup.4                                                                  3.8                                        8       31.8        7.8      3.9 × 10.sup.4                                                                  3.1                                        9       30.2        7.9      4.7 × 10.sup.4                                                                  3.1                                        10      31.9        8.0      5.2 × 10.sup.4                                                                  3.1                                         11*    53.8        6.3      8.4 × 10.sup.4                                                                  8.9                                        12      40.4        7.9      5.2 × 10.sup.4                                                                  4.0                                        13      42.8        8.3      6.1 × 10.sup.4                                                                  3.7                                        14      57.0        8.7      4.7 × 10.sup.4                                                                  3.6                                        15      69.1        9.6      4.3 × 10.sup.4                                                                  3.1                                         16*    203.0       7.3      2.1 × 10.sup.3                                                                  1.1                                        17      31.7        7.4      4.9 × 10.sup.4                                                                  3.4                                        18      27.5        7.9      5.5 × 10.sup.4                                                                  3.4                                        19      41.3        8.5      5.4 × 10.sup.4                                                                  3.2                                        20      38.4        8.9      4.9 × 10.sup.4                                                                  3.2                                        21      35.3        9.1      4.8 × 10.sup.4                                                                  3.1                                        22      30.7        9.4      4.8 × 10.sup.4                                                                  3.1                                        23      37.1        9.6      4.4 × 10.sup.4                                                                  3.1                                        24      40.4        9.1      6.5 × 10.sup.4                                                                  2.8                                        25      37.0        8.5      5.7 × 10.sup.4                                                                  3.5                                        26      39.0        9.4      6.9 × 10.sup.4                                                                  3.0                                        27      40.2        9.1      6.1 × 10.sup.4                                                                  3.4                                        28      55.1        10.3     4.8 × 10.sup.4                                                                  2.8                                        29      45.0        9.7      4.7 × 10.sup.4                                                                  3.2                                        30      47.2        9.4      4.3 × 10.sup.4                                                                  3.3                                         31*    206.7       9.0      1.9 × 10.sup.3                                                                  2.9                                        32      34.3        9.1      6.8 × 10.sup.4                                                                  2.9                                        33      41.0        9.4      6.2 × 10.sup.4                                                                  2.8                                        34      47.2        9.8      5.1 × 10.sup.4                                                                  2.7                                        35      48.0        9.7      4.4 × 10.sup.4                                                                  2.8                                        36      57.8        9.5      4.3 × 10.sup.4                                                                  2.7                                         37*    101.1       8.2      4.9 × 10.sup.4                                                                  4.0                                        ______________________________________                                          Marked * are comparison examples which are outside the claimed scope.    

<EXAMPLE 4>

After measuring SrCO₃ and TiO₂ in a manner that SrTiO₃ having Sr/Ti atom ratio of 0.98 is obtained, and they are blended and ground for 12 hours in wet method in a ball-mill or the like and dried. Then, the mixture is again ground, and thereafter, the ground powder is press-formed into a disk of a size of 80 mm diameter and 50 mm thickness by a pressing force of 1.0 ton/cm². The press-formed body then is calcinated at 1200° C. for 4 hours, and further ground by a ball-mill or the like for about 20 hours, thereby to prepare a host material powder of SrTiO₃.

Next, SrTiO₃, Y₂ O₃, Co₂ O₃, CuO, Ag₂ O and ZrO₂, and further, one of B₂ O₃, NiO, MoO₃, BeO, Fe₂ O₃, Al₂ O₃, Li₂ O, Cr₂ O₃, PbO, CaO, TiO₂, P₂ O₅, Sb₂ O₃, V₂ O₅ are measured in a composition ratio shown in Table 7, and press-formed and fired in the same manner as EXAMPLE 1. And the resulted element was measured in the similar conditions as those of EXAMPLE 1, and the results are shown in Table 8.

                                      TABLE 7                                      __________________________________________________________________________     Sample                                                                              Composition ratio (mol %)                                                 No.  SrTiO.sub.3                                                                        Y.sub.2 O.sub.3                                                                    Co.sub.2 O.sub.3                                                                   CuO Ag.sub.2 O                                                                          ZrO.sub.2                                                                           Additive                                        __________________________________________________________________________      1*  99.999                                                                             0.001                                                                              --  --  --   --   --                                               2*  99.998                                                                             0.001                                                                              0.001                                                                              --  --   --   --                                               3*  99.997                                                                             0.001                                                                              0.001                                                                              0.001                                                                              --   --   --                                               4*  99.996                                                                             0.001                                                                              0.001                                                                              0.001                                                                              0.001                                                                               --   --                                               5   99.995                                                                             0.001                                                                              0.001                                                                              0.001                                                                              0.001                                                                               0.001                                                                               --                                               6   99.986                                                                             0.010                                                                              0.001                                                                              0.001                                                                              0.001                                                                               0.001                                                                               --                                               7   99.896                                                                             0.100                                                                              0.001                                                                              0.001                                                                              0.001                                                                               0.001                                                                               --                                               8   98.996                                                                             1.000                                                                              0.001                                                                              0.001                                                                              0.001                                                                               0.001                                                                               --                                               9   97.996                                                                             2.000                                                                              0.001                                                                              0.001                                                                              0.001                                                                               0.001                                                                               --                                               10* 95.996                                                                             4.000                                                                              0.001                                                                              0.001                                                                              0.001                                                                               0.001                                                                               --                                              11   99.397                                                                             0.500                                                                              0.100                                                                              0.001                                                                              0.001                                                                               0.001                                                                               --                                              12   98.497                                                                             0.500                                                                              1.000                                                                              0.001                                                                              0.001                                                                               0.001                                                                               --                                              13   97.497                                                                             0.500                                                                              2.000                                                                              0.001                                                                              0.001                                                                               0.001                                                                               --                                               14* 95.497                                                                             0.500                                                                              4.000                                                                              0.001                                                                              0.001                                                                               0.001                                                                               --                                              15   99.298                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.001                                                                               0.001                                                                               --                                              16   98.398                                                                             0.500                                                                              0.100                                                                              1.000                                                                              0.001                                                                               0.001                                                                               --                                               17* 97.398                                                                             0.500                                                                              0.100                                                                              2.000                                                                              0.001                                                                               0.001                                                                               --                                              18   99.199                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.001                                                                               --                                              19   98.299                                                                             0.500                                                                              0.100                                                                              0.100                                                                              1.000                                                                               0.001                                                                               --                                               20* 97.299                                                                             0.500                                                                              0.100                                                                              0.100                                                                              2.000                                                                               0.001                                                                               --                                              21   99.100                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.100                                                                               --                                              22   98.200                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               1.000                                                                               --                                               23* 97.200                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               2.000                                                                               --                                              24   98.899                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               B.sub.2 O.sub.3                                                                    0.001                                       25   98.899                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               NiO 0.001                                       26   98.800                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               MoO.sub.3                                                                          0.100                                       27   98.800                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               Fe.sub.2 O.sub.3                                                                   0.100                                       28   97.900                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               Al.sub.2 O.sub.3                                                                   1.000                                       29   97.900                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               Li.sub.2 O.sub.3                                                                   1.000                                       30   96.900                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               CaO 2.000                                       31   96.900                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               TiO.sub.2                                                                          2.000                                        32* 94.900                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               B.sub.2 O.sub.3                                                                    4.000                                       33   98.790                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               B.sub.2 O.sub.3                                                                    0.010                                                                      Fe.sub.2 O.sub. 3                                                                  0.100                                       34   98.645                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               Al.sub.2 O.sub.3                                                                   0.100                                                                      Li.sub.2 O                                                                         0.005                                                                      CaO 0.100                                                                      TiO.sub.2                                                                          0.050                                       35   98.500                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               Cr.sub.2 O.sub.3                                                                   0.100                                                                      BeO 0.300                                       36   98.590                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               MoO.sub.3                                                                          0.300                                                                      P.sub.2 O.sub.5                                                                    0.010                                       37   98.650                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               Li.sub.2 O                                                                         0.050                                                                      Al.sub.2 O.sub.3                                                                   0.200                                        38* 96.400                                                                             0.500                                                                              0.100                                                                              0.100                                                                              0.100                                                                               0.300                                                                               NiO 0.500                                                                      Fe.sub.2 O.sub.3                                                                   1.000                                                                      CaO 1.000                                       __________________________________________________________________________      Marked * are comparison examples which are outside the claimed scope.    

                  TABLE 8                                                          ______________________________________                                         Sample                                                                         No.     V1mA/mm (V) α  ε                                                                             tan δ (%)                            ______________________________________                                          1*     83.0        1.3      1.0 × 10.sup.5                                                                  94.0                                        2*     50.6        6.0      1.9 × 10.sup.4                                                                  7.4                                         3*     35.2        6.2      3.1 × 10.sup.4                                                                  6.0                                         4*     39.7        6.5      4.0 × 10.sup.4                                                                  5.4                                         5      50.1        7.7      5.0 × 10.sup.4                                                                  3.0                                         6      48.7        7.6      5.2 × 10.sup.4                                                                  2.9                                         7      45.9        7.8      5.4 × 10.sup.4                                                                  2.8                                         8      60.0        8.0      5.3 × 10.sup.4                                                                  3.0                                         9      75.5        8.5      4.2 × 10.sup.4                                                                  2.9                                         10*    195.0       10.7     1.1 × 10.sup.3                                                                  2.9                                        11      54.0        8.1      4.9 × 10.sup.4                                                                  3.1                                        12      47.2        8.0      5.0 × 10.sup.4                                                                  3.0                                        13      44.5        8.0      5.7 × 10.sup.4                                                                  3.2                                         14*    56.2        4.7      7.0 × 10.sup.4                                                                  14.7                                       15      53.4        7.6      3.9 × 10.sup.4                                                                  2.9                                        16      88.7        8.4      3.8 × 10.sup.4                                                                  2.7                                         17*    203.1       10.5     1.6 × 10.sup.3                                                                  1.1                                        18      60.5        8.3      4.0 ×  10.sup.4                                                                 3.3                                        19      89.7        11.0     3.1 × 10.sup.4                                                                  3.0                                         20*    601.2       13.2     1.0 × 10.sup.3                                                                  0.9                                        21      52.7        7.6      5.9 × 10.sup.4                                                                  2.7                                        22      84.7        9.2      4.3 × 10.sup.4                                                                  2.6                                         23*    89.5        5.1      2.9 × 10.sup.4                                                                  12.7                                       24      55.0        9.4      3.8 × 10.sup.4                                                                  2.8                                        25      47.2        9.3      4.9 × 10.sup.4                                                                  2.6                                        26      50.3        9.5      5.0 × 10.sup.4                                                                  2.7                                        27      71.5        9.5      5.0 × 10.sup.4                                                                  2.6                                        28      85.4        10.2     4.1 × 10.sup.4                                                                  2.8                                        29      79.0        10.2     4.0 × 10.sup.4                                                                  2.8                                        30      98.1        10.2     4.1 × 10.sup.4                                                                  2.9                                        31      90.4        10.3     1.0 × 10.sup.4                                                                  2.7                                         32*    207.6       3.8      1.0 × 10.sup.3                                                                  7.9                                        33      59.7        9.1      4.0 × 10.sup.4                                                                  2.9                                        34      75.2        9.3      4.1 × 10.sup.4                                                                  2.6                                        35      77.1        10.1     4.2 × 10.sup.4                                                                  2.5                                        36      40.5        9.2      4.5 × 10.sup.4                                                                  3.1                                        37      63.3        9.8      3.9 × 10.sup.4                                                                  3.0                                         38*    259.0       10.4     1.1 × 10.sup.3                                                                  1.1                                        ______________________________________                                          Marked * are comparison examples which are outside the claimed scope.    

<EXAMPLE 5>

After measuring SrCO₃ and TiO₂ in a manner that SrTiO₃ having Sr/Ti atom ratio of 0.98 is obtained, and they are blended and ground for 12 hours in wet method in a ball-mill or the like and dried. Then, the mixture is again ground, and thereafter, the ground powder is press-formed into a disk of a size of 80 mm diameter and 50 mm thickness by a pressing force of 1.0 ton/cm². The press-formed body then is calcined at 1200° C. for 4 hours, and further ground by a ball-mill or the like for about 20 hours, thereby to preparee a host material powder of SrTiO₃.

Next, SrTiO₃, Y₂ O₃, Co₂ O₃, CuO, Ag₂ O and BaO, and further, one of B₂ O₃, NiO, MoO₃, BeO, Fe₂ O₃, Al₂ O₃, Li₂ O, Cr₂ O₃, PbO, CaO, TiO₂, P₂ O₅, Sb₂ O₃ and V₂ O₅ are measured in a composition ratio shown in Table 9, and press-formed and fired in the same manner as EXAMPLE 1. And the resultant element was measured in the similar conditions as those of EXAMPLE 1, and the results are shown in Table 10.

                  TABLE 9                                                          ______________________________________                                         Sam-                                                                           ple  Composition ratio (mol %)                                                 No.  SrTiO.sub.3                                                                            Y.sub.2 O.sub.3                                                                       Co.sub.2 O.sub.3                                                                     CuO  Ag.sub.2 O                                                                           BaO  Additive                             ______________________________________                                          1*  99.999  0.001  --    --   --    --   --                                    2*  99.998  0.001  0.001 --   --    --   --                                    3*  99.997  0.001  0.001 0.001                                                                               --    --   --                                    4*  99.996  0.001  0.001 0.001                                                                               0.001 --   --                                   5    99.995  0.001  0.001 0.001                                                                               0.001 0.001                                                                               --                                   6    99.986  0.010  0.001 0.001                                                                               0.001 0.001                                                                               --                                   7    99.896  0.100  0.001 0.001                                                                               0.001 0.001                                                                               --                                   8    98.996  1.000  0.001 0.001                                                                               0.001 0.001                                                                               --                                   9    97.996  2.000  0.001 0.001                                                                               0.001 0.001                                                                               --                                    10* 95.996  4.000  0.001 0.001                                                                               0.001 0.001                                                                               --                                   11   99.397  0.500  0.100 0.001                                                                               0.001 0.001                                                                               --                                   12   98.497  0.500  1.000 0.001                                                                               0.001 0.001                                                                               --                                   13   97.497  0.500  2.000 0.001                                                                               0.001 0.001                                                                               --                                    14* 95.497  0.500  4.000 0.001                                                                               0.001 0.001                                                                               --                                   15   99.298  0.500  0.100 0.100                                                                               0.001 0.001                                                                               --                                   16   98.398  0.500  0.100 1.000                                                                               0.001 0.001                                                                               --                                    17* 97.398  0.500  0.100 2.000                                                                               0.001 0.001                                                                               --                                   18   99.199  0.500  0.100 0.100                                                                               0.100 0.001                                                                               --                                   19   98.299  0.500  0.100 0.100                                                                               1.000 0.001                                                                               --                                    20* 97.299  0.500  0.100 0.100                                                                               2.000 0.001                                                                               --                                   21   99.100  0.500  0.100 0.100                                                                               0.100 0.100                                                                               --                                   22   98.200  0.500  0.100 0.100                                                                               0.100 1.000                                                                               --                                    23* 97.200  0.500  0.100 0.100                                                                               0.100 2.000                                                                               --                                   24   98.899  0.500  0.100 0.100                                                                               0.100 0.300                                                                               B.sub.2 O.sub.3                                                                      0.001                          25   98.899  0.500  0.100 0.100                                                                               0.100 0.300                                                                               NiO   0.001                          26   98.800  0.500  0.100 0.100                                                                               0.100 0.300                                                                               MoO.sub.3                                                                            0.001                          27   98.800  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Fe.sub.2 O.sub.3                                                                     0.100                          28   97.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Al.sub.2 O.sub.3                                                                     1.000                          29   97.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Li.sub.2 O                                                                           1.000                          30   96.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               CaO   2.000                          31   96.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               TiO.sub.2                                                                            2.000                           32* 94.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               B.sub.2 O.sub.3                                                                      4.000                          33   98.790  0.500  0.100 0.100                                                                               0.100 0.300                                                                               B.sub.2 O.sub.3                                                                      0.010                                                                    Fe.sub. 2 O.sub.3                                                                    0.100                          34   98.645  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Al.sub.2 O.sub.3                                                                     0.100                                                                    Li.sub.2 O                                                                           0.005                                                                    CaO   0.100                                                                    TiO.sub.2                                                                            0.050                          35   98.500  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Fe.sub.2 O.sub.3                                                                     0.100                                                                    V.sub.2 O.sub.5                                                                      0.300                          36   98.590  0.500  0.100 0.100                                                                               0.100 0.300                                                                               BeO   0.300                                                                    P.sub.2 O.sub.5                                                                      0.010                          37   98.650  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Cr.sub.2 O.sub.3                                                                     0.050                                                                    TiO.sub.2                                                                            0.200                           38* 96.400  0.500  0.100 0.100                                                                               0.100 0.300                                                                               MoO.sub.3                                                                            0.500                                                                    Sb.sub.2 O.sub.3                                                                     1.000                                                                    Al.sub.2 O.sub.3                                                                     1.000                          ______________________________________                                          Marked * are comparison examples which are outside the claimed scope.    

                  TABLE 10                                                         ______________________________________                                         Sample                                                                         No.    V.sub.1 mA/mm (V)                                                                          α  ε                                                                             tan δ (%)                             ______________________________________                                          1*    83.0        1.3      1.0 × 10.sup.6                                                                  94.0                                         2*    50.6        6.0      1.9 × 10.sup.4                                                                  7.4                                          3*    35.2        6.2      3.1 × 10.sup.4                                                                  6.0                                          4*    39.7        6.5      4.0 × 10.sup.4                                                                  5.4                                          5     40.0        7.2      6.5 × 10.sup.4                                                                  3.1                                          6     37.8        7.1      6.6 × 10.sup.4                                                                  3.0                                          7     39.5        7.3      6.9 × 10.sup.4                                                                  3.0                                          8     51.1        7.6      6.7 × 10.sup.4                                                                  3.0                                          9     60.7        8.4      5.8 × 10.sup.4                                                                  3.0                                          10*   158.9       10.1     1.2 × 10.sup.3                                                                  3.0                                         11     44.2        7.9      5.8 × 10.sup.4                                                                  3.1                                         12     39.3        7.9      6.4 × 10.sup.4                                                                  3.1                                         13     35.6        8.0      7.3 × 10.sup.4                                                                  3.1                                          14*   45.3        4.1      8.4 × 10.sup.4                                                                  16.2                                        15     45.4        7.3      5.3 × 10.sup.4                                                                  2.9                                         16     78.1        8.1      5.1 × 10.sup.4                                                                  2.8                                          17*   185.3       10.2     1.3 × 10.sup.3                                                                  1.5                                         18     50.9        8.0      5.5 × 10.sup.4                                                                  3.5                                         19     77.9        10.6     4.9 × 10.sup.4                                                                  3.0                                          20*   420.2       11.9     1.1 × 10.sup.3                                                                  1.0                                         21     40.5        7.2      6.4 × 10.sup.4                                                                  2.9                                         22     75.3        8.9      5.7 × 10.sup.4                                                                  2.9                                          23*   80.9        4.6      3.0 × 10.sup.4                                                                  16.4                                        24     47.5        9.2      4.5 × 10.sup.4                                                                  3.0                                         25     39.3        9.3      4.9 × 10.sup.4                                                                  2.9                                         26     40.4        9.3      5.8 × 10.sup.4                                                                  2.9                                         27     65.2        9.3      6.1 × 10.sup.4                                                                  2.8                                         28     74.9        10.0     5.7 × 10.sup.4                                                                  2.8                                         29     69.8        10.1     5.5 × 10.sup.4                                                                  2.9                                         30     89.4        10.2     5.5 × 10.sup.4                                                                  2.8                                         31     80.8        10.3     1.4 × 10.sup.4                                                                  2.8                                          32*   157.6       3.7      1.0 × 10.sup.3                                                                  9.1                                         33     42.0        9.0      5.2 × 10.sup.4                                                                  3.0                                         34     69.2        9.1      5.3 × 10.sup.4                                                                  2.9                                         35     69.9        9.8      5.7 × 10.sup.4                                                                  2.4                                         36     35.3        9.0      5.1 × 10.sup.4                                                                  3.1                                         37     57.8        9.4      4.3 × 10.sup.4                                                                  3.1                                          38*   191.6       10.1     1.0 × 10.sup.3                                                                  1.7                                         ______________________________________                                          Marked * are comparison examples which are outside the claimed scope.    

<EXAMPLE 6>

After measuring SrCO₃ and TiO₂ in a manner that SrTiO₃ having Sr/Ti atom ratio of 0.98 is obtained, and they are blended and ground for 12 hours in wet method in a ball-mill or the like and dried. Then, the mixture is again ground, and thereafter, the ground powder is press-formed into a disk of a size of 80 mm diameter and 50 mm thickness by a pressing force of 1.0 ton/cm². The press-formed body than is calcinated at 1200° C. for 4 hours, and further ground by a ball-mill or the like for about 20 hours, thereby to prepare a host material powder of SrTiO₃.

Next, SrTiO₃, Y₂ O₃, Co₂ O₃, CuO, Ag₂ O and SiO₂, and further, one of B₂ O₃, MnO₂, NiO, MoO₃, BeO, Fe₂ O₃, Al₂ O₃, Li₂ O, Cr₂ O₃, ZrO₂, PbO, BaO, CaO, MgO, TiO₂, ZnO, P₂ O₅, Sb₂ O₃ and v₂ O₅ are measured in a composition ratio shown in Table 11, and press-formed and fired in the same manner as EXAMPLE 1. And the resultant element was measured in the similar conditions as those of EXAMPLE 1, and the results are shown in Table 12.

                  TABLE 11                                                         ______________________________________                                         Sam-                                                                           ple  Composition ratio (mol %)                                                 No.  SrTiO.sub.3                                                                            Y.sub.2 O.sub.3                                                                       Co.sub.2 O.sub.3                                                                     CuO  Ag.sub.2 O                                                                           SiO.sub.2                                                                           Additive                             ______________________________________                                          1*  99.999  0.001  --    --   --    --   --                                    2*  99.998  0.001  0.001 --   --    --   --                                    3*  99.997  0.001  0.001 0.001                                                                               --    --   --                                    4*  99.996  0.001  0.001 0.001                                                                               0.001 --   --                                    5   99.995  0.001  0.001 0.001                                                                               0.001 0.001                                                                               --                                    6   99.986  0.010  0.001 0.001                                                                               0.001 0.001                                                                               --                                    7   99.896  0.100  0.001 0.001                                                                               0.001 0.001                                                                               --                                    8   98.996  1.000  0.001 0.001                                                                               0.001 0.001                                                                               --                                    9   97.996  2.000  0.001 0.001                                                                               0.001 0.001                                                                               --                                    10* 95.996  4.000  0.001 0.001                                                                               0.001 0.001                                                                               --                                   11   99.397  0.500  0.100 0.001                                                                               0.001 0.001                                                                               --                                   12   98.497  0.500  1.000 0.001                                                                               0.001 0.001                                                                               --                                   13   97.497  0.500  2.000 0.001                                                                               0.001 0.001                                                                               --                                    14* 95.497  0.500  4.000 0.001                                                                               0.001 0.001                                                                               --                                   15   99.298  0.500  0.100 0.100                                                                               0.001 0.001                                                                               --                                   16   98.398  0.500  0.100 1.000                                                                               0.001 0.001                                                                               --                                    17* 97.398  0.500  0.100 2.000                                                                               0.001 0.001                                                                               --                                   18   99.199  0.500  0.100 0.100                                                                               0.100 0.001                                                                               --                                   19   98.299  0.500  0.100 0.100                                                                               1.000 0.001                                                                               --                                    20* 97.299  0.500  0.100 0.100                                                                               2.000 0.001                                                                               --                                   21   99.100  0.500  0.100 0.100                                                                               0.100 0.100                                                                               --                                   22   98.200  0.500  0.100 0.100                                                                               0.100 1.000                                                                               --                                    23* 97.200  0.500  0.100 0.100                                                                               0.100 2.000                                                                               --                                   24   98.899  0.500  0.100 0.100                                                                               0.100 0.300                                                                               B.sub.2 O.sub.3                                                                      0.001                          25   98.899  0.500  0.100 0.100                                                                               0.100 0.300                                                                               NiO   0.001                          26   98.800  0.500  0.100 0.100                                                                               0.100 0.300                                                                               MoO.sub.3                                                                            0.100                          27   98.800  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Fe.sub.2 O.sub.3                                                                     0.100                          28   97.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Al.sub.2 O.sub.3                                                                     1.000                          29   97.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Li.sub.2 O                                                                           1.000                          30   96.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               CaO   2.000                          31   96.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               TiO.sub.2                                                                            2.000                           32* 94.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               B.sub.2 O.sub.3                                                                      4.000                          33   98.790  0.500  0.100 0.100                                                                               0.100 0.300                                                                               B.sub.2 O.sub.3                                                                      0.010                                                                    Fe.sub.2 O.sub.3                                                                     0.100                          34   98.645  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Al.sub.2 O.sub.3                                                                     0.100                                                                    Li.sub.2 O                                                                           0.005                                                                    CaO   0.100                                                                    TiO.sub.2                                                                            0.050                          35   98.500  0.500  0.100 0.100                                                                               0.100 0.300                                                                               MnO.sub.2                                                                            0.100                                                                    Al.sub.2 O.sub.3                                                                     0.300                          36   98.887  0.500  0.100 0.100                                                                               0.100 0.300                                                                               BaO   0.010                                                                    Li.sub.2 O                                                                           0.003                          37   98.500  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Al.sub.2 O.sub.3                                                                     0.100                                                                    MgO   0.300                          38   98.400  0.500  0.100 0.100                                                                               0.100 0.300                                                                               TiO.sub.2                                                                            0.050                                                                    ZrO.sub.2                                                                            0.150                                                                    MnO.sub.2                                                                            0.300                           39* 96.390  0.500  0.100 0.100                                                                               0.100 0.300                                                                               MgO   1.500                                                                    MnO.sub.2                                                                            1.000                                                                    TiO.sub.2                                                                            0.010                          ______________________________________                                          Marked * are comparison examples which are outside the claimed scope.    

                  TABLE 12                                                         ______________________________________                                         Sample                                                                         No.     V.sub.1 mA/mm (V)                                                                          α  ε                                                                             tan δ (%)                            ______________________________________                                          1*     83.0        1.3      1.0 × 10.sup.6                                                                  91.0                                        2*     50.6        6.0      1.9 × 10.sup.4                                                                  7.4                                         3*     35.2        6.2      3.1 × 10.sup.4                                                                  6.0                                         4*     39.7        6.5      4.0 × 10.sup.4                                                                  5.4                                         5      43.2        7.8      6.2 × 10.sup.4                                                                  3.1                                         6      41.9        7.6      6.3 × 10.sup.4                                                                  3.3                                         7      40.0        7.7      6.5 × 10.sup.4                                                                  3.3                                         8      52.4        7.9      5.7 × 10.sup.4                                                                  3.1                                         9      70.1        8.8      5.3 × 10.sup.4                                                                  2.7                                         10*    155.0       9.7      2.0 × 10.sup.3                                                                  2.2                                        11      40.9        7.8      5.3 × 10.sup.4                                                                  3.2                                        12      37.3        7.7      5.5 × 10.sup.4                                                                  3.7                                        13      38.7        7.1      6.1 × 10.sup.4                                                                  4.3                                         14*    45.1        5.7      8.0 × 10.sup.4                                                                  28.9                                       15      47.2        7.2      4.3 × 10.sup.4                                                                  3.1                                        16      89.0        8.9      4.1 × 10.sup.4                                                                  2.4                                         17*    304.9       11.4     1.9 × 10.sup.3                                                                  1.0                                        18      52.3        8.0      4.5 × 10.sup.4                                                                  2.8                                        19      94.0        10.9     4.1 × 10.sup.4                                                                  2.3                                         20*    909.4       15.3     1.1 × 10.sup.3                                                                  0.9                                        21      49.7        8.0      6.3 × 10.sup.4                                                                  3.0                                        22      80.5        9.4      5.1 × 10.sup.4                                                                  2.7                                         23*    84.9        6.9      2.8 × 10.sup.4                                                                  11.5                                       24      51.3        9.7      3.9 × 10.sup.4                                                                  3.2                                        25      40.9        9.2      5.3 × 10.sup.4                                                                  3.5                                        26      43.4        9.5      5.5 × 10.sup.4                                                                  3.4                                        27      62.1        9.5      4.7 × 10.sup.4                                                                  2.7                                        28      75.5        10.1     4.2 × 10.sup.4                                                                  2.4                                        29      74.0        10.0     4.3 × 10.sup.4                                                                  2.1                                        30      97.1        10.3     3.8 × 10.sup.4                                                                  2.2                                        31      88.8        10.5     3.5 × 10.sup.4                                                                  2.3                                         32*    210.4       4.1      1.7 × 10.sup.3                                                                  3.9                                        33      55.1        9.1      4.3 × 10.sup.4                                                                  2.2                                        34      70.8        9.7      5.0 × 10.sup.4                                                                  2.0                                        35      75.0        10.9     4.9 × 10.sup.4                                                                  2.0                                        36      54.0        9.2      5.7 × 10.sup.4                                                                  2.9                                        37      64.3        9.5      5.5 × 10.sup.4                                                                  2.7                                        38      102.5       10.8     3.9 × 10.sup.4                                                                  1.5                                         39*    899.0       16.5     1.0 × 10.sup.3                                                                  0.8                                        ______________________________________                                          Marked * are comparison examples which are outside the claimed scope.    

<EXAMPLE 7>

After measuring SrCO₃ and TiO₂ in a manner that SrTiO₃ having Sr/Ti atom ratio of 0.98 is obtained, and they are blended and ground for 12 hours in wet method in a ball-mill or the like and dried. Then, the mixture is again ground, and thereafter, the ground powder is press-formed into a disk of a size of 80 mm diameter and 50 mm thickness by a pressing force of 1.0 ton/cm². The press-formed body then is calcinated at 1200° C. for 4 hours, and further ground by a ball-mill or the like for about 20 hours, thereby to prepare a host material powder of SrTiO₃.

Next, SrTiO₃, Y₂ O₃, Co₂ O₃, CuO, Ag₂ O and SiO₂, and further, one of B₂ O₃, MnO₂, NiO, MoO₃, BeO, Fe₂ O₃, Al₂ O₃, Li₂ O, Cr₂ O₃, ZrO₂, PbO, BaO, CaO, MgO, TiO₂, ZnO, P₂ O₅, Sb₂ O₃ and V₂ O₅ are measured in a composition ratio shown in Table 13, and press-formed and fired in the same manner as EXAMPLE 1. And the resultant element was measured in the similar conditions as those of EXAMPLE 1, and the results are shown in Table 14.

                  TABLE 13                                                         ______________________________________                                         Sam-                                                                           ple  Comparison ratio (mol %)                                                  No.  SrTiO.sub.3                                                                            Y.sub.2 O.sub.3                                                                       Co.sub.2 O.sub.3                                                                     CuO  Ag.sub.2 O                                                                           MgO  Additive                             ______________________________________                                          1*  99.999  0.001  --    --   --    --   --                                    2*  99.998  0.001  0.001 --   --    --   --                                    3*  99.997  0.001  0.001 0.001                                                                               --    --   --                                    4*  99.996  0.001  0.001 0.001                                                                               0.001 --   --                                    5   99.995  0.001  0.001 0.001                                                                               0.001 0.001                                                                               --                                    6   99.986  0.010  0.001 0.001                                                                               0.001 0.001                                                                               --                                    7   99.896  0.100  0.001 0.001                                                                               0.001 0.001                                                                               --                                    8   98.996  1.000  0.001 0.001                                                                               0.001 0.001                                                                               --                                    9   97.996  2.000  0.001 0.001                                                                               0.001 0.001                                                                               --                                    10* 95.996  4.000  0.001 0.001                                                                               0.001 0.001                                                                               --                                   11   99.397  0.500  0.100 0.001                                                                               0.001 0.001                                                                               --                                   12   98.497  0.500  1.000 0.001                                                                               0.001 0.001                                                                               --                                   13   97.497  0.500  2.000 0.001                                                                               0.001 0.001                                                                               --                                    14* 95.497  0.500  4.000 0.001                                                                               0.001 0.001                                                                               --                                   15   99.298  0.500  0.100 0.100                                                                               0.001 0.001                                                                               --                                   16   98.398  0.500  0.100 1.000                                                                               0.001 0.001                                                                               --                                    17* 97.398  0.500  0.100 2.000                                                                               0.001 0.001                                                                               --                                   18   99.199  0.500  0.100 0.100                                                                               0.100 0.001                                                                               --                                   19   98.299  0.500  0.100 0.100                                                                               1.000 0.001                                                                               --                                    20* 97.299  0.500  0.100 0.100                                                                               2.000 0.001                                                                               --                                   21   99.100  0.500  0.100 0.100                                                                               0.100 0.100                                                                               --                                   22   98.200  0.500  0.100 0.100                                                                               0.100 1.000                                                                               --                                    23* 97.200  0.500  0.100 0.100                                                                               0.100 2.000                                                                               --                                   24   98.899  0.500  0.100 0.100                                                                               0.100 0.300                                                                               B.sub.2 O.sub.3 0.001                25   98.899  0.500  0.100 0.100                                                                               0.100 0.300                                                                               NiO 0.001                            26   98.800  0.500  0.100 0.100                                                                               0.100 0.300                                                                               MoO.sub.3 0.100                      27   98.800  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Fe.sub.2 O.sub.3 0.100               28   97.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Al.sub.2 O.sub.3 1.000               29   97.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Li.sub.2 O 1.000                     30   96.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               CaO 2.000                            31   96.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               TiO.sub.2 2.000                       32* 94.900  0.500  0.100 0.100                                                                               0.100 0.300                                                                               B.sub.2 O.sub.3 4.000                33   98.790  0.500  0.100 0.100                                                                               0.100 0.300                                                                               B.sub.2 O.sub.3 0.010                                                          Fe.sub.2 O.sub.3 0.100               34   98.645  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Al.sub.2 O.sub.3 0.100                                                         Li.sub.2 O 0.005                                                               CaO 0.100                                                                      TiO.sub.2 0.050                      35   98.300  0.500  0.100 0.100                                                                               0.100 0.300                                                                               V.sub.2 O.sub.5 0.100                                                          CaO 0.500                            36   98.350  0.500  0.100 0.100                                                                               0.100 0.300                                                                               Sb.sub.2 O.sub.3 0.050                                                         TiO.sub.2 0.500                      37   98.100  0.500  0.100 0.100                                                                               0.100 0.300                                                                               NiO 0.300                                                                      Al.sub.2 O.sub.3 0.500                38* 96.795  0.500  0.100 0.100                                                                               0.100 0.300                                                                               BeO 0.005                                                                      Cr.sub.2 O.sub.3 1.100                                                         CaO 1.000                            ______________________________________                                          Marked * are comparison examples which are outside the claimed scope.    

                  TABLE 14                                                         ______________________________________                                         Sample                                                                         No.     V.sub.1 mA/mm (V)                                                                          α  ε                                                                             tanδ (%)                             ______________________________________                                          1*     83.0        1.3      1.0 × 10.sup.6                                                                  94.0                                        2*     50.6        6.0      1.9 × 10.sup.4                                                                  7.4                                         3*     35.2        6.2      3.1 × 10.sup.4                                                                  6.0                                         4*     39.7        6.5      4.0 × 10.sup.4                                                                  5.4                                         5      48.1        7.5      4.9 × 10.sup.4                                                                  2.9                                         6      46.5        7.7      5.1 × 10.sup.4                                                                  2.8                                         7      43.8        7.8      5.2 × 10.sup.4                                                                  2.7                                         8      55.7        8.1      5.3 × 10.sup.4                                                                  2.9                                         9      73.6        8.4      4.3 × 10.sup.4                                                                  2.8                                         10*    181.0       9.8      1.0 × 10.sup.3                                                                  2.8                                        11      51.5        8.2      4.8 × 10.sup.4                                                                  2.8                                        12      45.3        8.2      5.1 × 10.sup.4                                                                  2.8                                        13      41.6        8.1      5.6 × 10.sup.4                                                                  2.9                                         14*    55.0        4.4      6.1 × 10.sup.4                                                                  11.5                                       15      52.2        7.7      4.2 × 10.sup.4                                                                  2.7                                        16      87.8        8.3      4.1 × 10.sup.4                                                                  2.5                                         17*    180.5       10.2     1.3 × 10.sup.3                                                                  0.7                                        18      58.3        8.1      4.2 × 10.sup.4                                                                  2.9                                        19      87.7        10.7     3.9 × 10.sup.4                                                                  2.9                                         20*    349.1       12.9     1.1 × 10.sup.3                                                                  0.9                                        21      50.5        7.2      5.7 × 10.sup.4                                                                  2.5                                        22      82.2        9.0      4.1 × 10.sup.4                                                                  2.4                                         23*    85.8        5.2      1.9 × 10.sup.4                                                                  11.9                                       24      54.1        9.2      3.9 × 10.sup.4                                                                  1.8                                        25      42.3        9.3      4.7 × 10.sup.4                                                                  1.4                                        26      47.8        9.4      4.9 × 10.sup.4                                                                  1.7                                        27      65.6        9.5      5.0 × 10.sup.4                                                                  1.8                                        28      80.5        10.0     4.2 × 10.sup.4                                                                  1.5                                        29      66.3        10.0     4.1 × 10.sup.4                                                                  1.7                                        30      93.4        10.1     4.1 × 10.sup.4                                                                  1.4                                        31      84.4        10.0     1.0 × 10.sup.4                                                                  1.4                                         32*    172.3       2.4      1.0 × 10.sup.3                                                                  9.5                                        33      57.2        9.0      4.1 × 10.sup.4                                                                  2.0                                        34      81.8        9.2      4.1 × 10.sup.4                                                                  1.7                                        35      55.3        10.2     4.4 × 10.sup.4                                                                  1.8                                        36      70.4        10.3     4.7 × 10.sup.4                                                                  1.4                                        37      78.5        10.5     4.3 × 10.sup.4                                                                  1.4                                         38*    241.9       11.7     1.1 × 10.sup.3                                                                  0.9                                        ______________________________________                                          Marked * are comparison examples which are outside the claimed scope.    

<EXAMPLE 8>

After measuring SrCO₃ and TiO₂ in a manner that SrTiO₃ having Sr/Ti atom ratio of 0.98 is obtained, and they are blended and ground for 12 hours in wet method in a ball-mill or the like and dried. Then, the mixture is again ground, and thereafter, the ground powder is press-formed into a disk of a size of 80 mm diameter and 50 mm thickness by a pressing force of 1.0 ton/cm². The press-formed body then is calcinated at 1200° C. for 4 hours, and further ground by a ball-mill or the like for about 20 hours, thereby to prepare a host material powder of SrTiO₃.

Next, SrTiO₃, Y₂ O₃, Co₂ O₃, CuO, Ag₂ O and MnO₂, and further, one of B₂ O₃, NiO, MoO₃, BeO, Fe₂ O₃, Al₂ O₃, Li₂ O, Cr₂ O₃, PbO, CaO, TiO₂, P₂ O₅, Sb₂ O₃ and V₂ O₅ are measured in a composition ratio shown in Table 15, and press-formed and fired in the same manner as EXAMPLE 1. And the resultant element was measured in the similar conditions as those of EXAMPLE 1, and the results are shown in Table 16.

                  TABLE 15                                                         ______________________________________                                         Sam-                                                                           ple  Composition ratio                                                         No.  SrTiO.sub.3                                                                            Y.sub.2 O.sub.3                                                                       Co.sub.2 O.sub.3                                                                     CuO  Ag.sub.2 O                                                                           MnO.sub.2                                                                            Additive                            ______________________________________                                          1*  99.999  0.001  --    --   --    --    --                                   2*  99.998  0.001  0.001 --   --    --    --                                   3*  99.997  0.001  0.001 0.001                                                                               --    --    --                                   4*  99.996  0.001  0.001 0.001                                                                               0.001 --    --                                   5   99.995  0.001  0.001 0.001                                                                               0.001 0.001 --                                   6   99.986  0.010  0.001 0.001                                                                               0.001 0.001 --                                   7   99.896  0.100  0.001 0.001                                                                               0.001 0.001 --                                   8   98.996  1.000  0.001 0.001                                                                               0.001 0.001 --                                   9   97.996  2.000  0.001 0.001                                                                               0.001 0.001 --                                   10* 95.996  4.000  0.001 0.001                                                                               0.001 0.001 --                                  11   99.397  0.500  0.100 0.001                                                                               0.001 0.001 --                                  12   98.497  0.500  1.000 0.001                                                                               0.001 0.001 --                                  13   97.497  0.500  2.000 0.001                                                                               0.001 0.001 --                                   14* 95.497  0.500  4.000 0.001                                                                               0.001 0.001 --                                  15   99.298  0.500  0.100 0.100                                                                               0.001 0.001 --                                  16   98.398  0.500  0.100 1.000                                                                               0.001 0.001 --                                   17* 97.398  0.500  0.100 2.000                                                                               0.001 0.001 --                                  18   99.199  0.500  0.100 0.100                                                                               0.100 0.001 --                                  19   98.299  0.500  0.100 0.100                                                                               1.000 0.001 --                                   20* 97.299  0.500  0.100 0.100                                                                               2.000 0.001 --                                  21   99.100  0.500  0.100 0.100                                                                               0.100 0.100 --                                  22   98.200  0.500  0.100 0.100                                                                               0.100 1.000 --                                   23* 97.200  0.500  0.100 0.100                                                                               0.100 2.000 --                                  24   98.899  0.500  0.100 0.100                                                                               0.100 0.300 B.sub.2 O.sub.3 0.001               25   98.899  0.500  0.100 0.100                                                                               0.100 0.300 NiO 0.001                           26   98.800  0.500  0.100 0.100                                                                               0.100 0.300 MoO.sub.3 0.100                     27   98.800  0.500  0.100 0.100                                                                               0.100 0.300 Fe.sub.2 O.sub.3                                                               0.100                               28   97.900  0.500  0.100 0.100                                                                               0.100 0.300 Al.sub.2 O.sub.3 1.000              29   97.900  0.500  0.100 0.100                                                                               0.100 0.300 Li.sub.2 O 1.000                    30   96.900  0.500  0.100 0.100                                                                               0.100 0.300 CaO 2.000                           31   96.900  0.500  0.100 0.100                                                                               0.100 0.300 TiO.sub.2 2.000                      32* 94.900  0.500  0.100 0.100                                                                               0.100 0.300 B.sub.2 O.sub.3 4.000               33   98.790  0.500  0.100 0.100                                                                               0.100 0.300 B.sub.2 O.sub. 3 0.100                                                         Fe.sub.2 O.sub.3                                                               0.100                               34   98.645  0.500  0.100 0.100                                                                               0.100 0.300 Al.sub.2 O.sub.3 0.100                                                         Li.sub.2 O 0.005                                                               CaO 0.100                                                                      TiO.sub.2 0.050                     35   98.500  0.500  0.100 0.100                                                                               0.100 0.300 MoO.sub.3 0.100                                                                CaO 0.300                           36   98.887  0.500  0.100 0.100                                                                               0.100 0.300 PbO 0.010                                                                      Al.sub.2 O.sub.3 0.300              37   98.445  0.500  0.100 0.100                                                                               0.100 0.300 Fe.sub.2 O.sub.3 0.005                                                         Cr.sub.2 O.sub.3                                                               0.150                                                                          TiO.sub.2 0.300                      38* 96.300  0.500  0.100 0.100                                                                               0.100 0.300 BeO 0.100                                                                      Li.sub.2 O 1.000                                                               CaO 1.500                           ______________________________________                                          Marked * are comparison examples which are outside the claimed scope.    

                  TABLE 16                                                         ______________________________________                                         Sample                                                                         No.    V.sub.1 mA/mm (V)                                                                          α  ε                                                                             tan δ (%)                             ______________________________________                                          1*    83.0        1.3      1.0 × 10.sup.6                                                                  94.0                                         2*    50.6        6.0      1.9 × 10.sup.4                                                                  7.4                                          3*    35.2        6.2      3.1 × 10.sup.4                                                                  6.0                                          4*    39.7        6.5      4.0 × 10.sup.4                                                                  5.4                                          5     55.3        8.0      6.0 × 10.sup.4                                                                  3.5                                          6     53.9        8.7      6.1 × 10.sup.4                                                                  3.4                                          7     50.5        8.9      6.4 × 10.sup.4                                                                  3.6                                          8     64.2        9.1      5.6 × 10.sup.4                                                                  3.3                                          9     80.5        9.9      4.8 × 10.sup.4                                                                  3.2                                          10*   209.4       10.5     1.5 × 10.sup.3                                                                  3.1                                         11     59.0        9.1      5.2 × 10.sup.4                                                                  3.4                                         12     48.7        8.9      5.3 × 10.sup.4                                                                  3.5                                         13     48.8        8.5      5.9 × 10.sup.4                                                                  4.4                                          14*   55.9        5.5      7.5 × 10.sup.4                                                                  30.4                                        15     58.2        7.4      4.5 × 10.sup.4                                                                  3.0                                         16     100.0       8.9      3.9 × 10.sup.4                                                                  2.8                                          17*   341.3       12.0     1.7 × 10.sup.3                                                                  0.9                                         18     63.4        8.5      4.0 × 10.sup.4                                                                  3.3                                         19     100.9       11.3     3.8 × 10.sup.4                                                                  2.9                                          20*   814.4       14.8     1.2 × 10.sup.3                                                                  0.8                                         21     57.9        8.1      6.1 × 10.sup.4                                                                  3.1                                         22     92.4        9.5      4.4 × 10.sup.4                                                                  3.0                                          23*   95.9        6.5      3.1 × 10.sup.4                                                                  15.2                                        24     63.2        9.8      4.3 × 10.sup.4                                                                  3.3                                         25     51.8        9.5      5.0 × 10.sup.4                                                                  3.4                                         26     54.6        9.7      5.1 × 10.sup.4                                                                  3.5                                         27     75.3        9.5      4.3 × 10.sup.4                                                                  3.1                                         28     89.5        9.3      4.0 × 10.sup.4                                                                  3.0                                         29     83.4        9.2      4.0 × 10.sup.4                                                                  2.9                                         30     108.9       9.3      4.5 × 10.sup.4                                                                  2.8                                         31     99.0        9.6      3.4 × 10.sup.4                                                                  2.8                                          32*   354.1       4.0      1.0 × 10.sup.3                                                                  4.4                                         33     63.8        9.2      3.9 × 10.sup.4                                                                  2.5                                         34     81.5        9.6      4.0 × 10.sup.4                                                                  2.4                                         35     60.5        9.9      5.2 × 10.sup.4                                                                  2.3                                         36     45.4        9.0      5.6 × 10.sup.4                                                                  3.2                                         37     95.7        10.4     3.8 × 10.sup.4                                                                  3.0                                          38*   385.2       15.1     1.0 × 10.sup.3                                                                  0.9                                         ______________________________________                                          Marked * are comparison examples which are outside the claimed scope.    

As shown by the EXAMPLES 1-3, addition of Y₂ O₃ accelerates semiconductorization of SrTiO₃, Sr_(1-x) Ba_(x) TiO₃ and Sr_(1-x) Ca_(x) TiO₃, and thereby can decrease specific resistance when the reducing firing is made and shows varistor characteristic when it is reoxidized in the air. However, when the additive is only Y₂ O₃, the α is small and the tan δ is large, and the element is not suitable for actual use.

Additions of Co₂ O₃ and CuO induce increase of α and decrease of tan δ.

Additions of Ag₂ O or Al₂ O₃ improves varistor characteristics, keeping the capacitor characteristics.

The reason of the above-mentioned changes of characteristics by the additions is that these additives segregate at grain boundaries, thereby selectively increasing the resistance of the grain boundaries. The grain boundaries of high resistance formed in this way functions as capacitors with very short gap between electrodes, as well as as varistor. Therefore, the resultant element becomes a varistor having a large capacity.

As the additives to make the grain boundary selectively to a high resistance to give the characteristics of a capacitor and a varistor at the same time, ZrO₂, BaO, SiO₂, MgO, MnO₂, B₂ O₃, NiO, MoO₃, BeO, Fe₂ O₃, Li₂ O, Cr₂ O₃, PbO, CaO, TiO₂, P₂ O₅, Sb₂ O₃ and V₂ O₅ are especially effective.

These additives make effect when added in an amount of over 0.001 mol %, but when the amount exceeds 3.000 mol % the characteristic becomes poor. The reason of the characteristic becoming poor is due to increase of thickness of grain boundaries, hence decrease of capacitance thereof, which induces increase of varistor voltage and deterioration of varistor characteristic.

The average diameter of the grain of the element is about 100 μm, and the larger the diameter becomes the more effective in lowering varistor voltage.

Besides, the additives mentioned in the above-mentioned EXAMPLES, other additives, such as two or more kinds of oxides selected from the group consisting of ZrO₂, BaO, SiO₂, MgO, MnO₂, B₂ O₃, NiO, MoO₃, BeO, Fe₂ O₃, LiO₂, Cr₂ O₃, PbO, CaO, TiO₂, P₂ O₅, Sb₂ O₃ and V₂ O₅ can be used, and in such case the similar good effect is obtainable.

With respect to the ratio of Sr/Ti is regarded to be effective on the dielectric characteristic of the dielectric substance of grain boundary type. For instance, the relation between Sr/Ti ratio and specific resistance ρ and tan δ of the completed element are as shown in FIG. 6 and FIG. 7. As can be understood from these graphs, when the ratio Sr/Ti differs from 1 the specific resistance ρ decreases and the semiconductorization is accelerated. Accordingly, the dielectric constant ε increases. On the other hand, as the ratio Sr/Ti differs from 1, the value tan δ increases. Accordingly, in actual element, the Sr/Ti ratio within a range of 1.05-0.95 is desirable in view of the harmoney between the specific resistance ρ and tan δ.

On an element manufactured in the above-mentioned process, electrodes were provided by, for instance, conductive paint containing conductive material such as Ag or the like, to complete a capacitor-varistor complex element to serve as a noise filter shown in FIG. 4. When noise A shown in FIG. 5 was impressed on the complex element, the output B of FIG. 5 was obtained. As is obvious from comparison of the curve A with the curve B, noise is satisfactorily removed for all range of frequency by this complex element filter. This is in contradistinction to the conventional filter shown by the curve C when noise elimination is not satisfactorily for all range, especially in the low frequency range. This filter is advantageous in comprising very few component parts and having no internal connection and hence, compactness of the configuration and size. The filter in accordance with the present invention is suitable for noise suppressing circuit in various kinds of electric and electronic appliances which is necessary for a protection of semiconductor devices in such appliances, and is very useful in industrial application. 

What is claimed is:
 1. A voltage-dependent non-linear resistance ceramic composition consisting essentially of:95.000-99.997 mol % of SrTiO₃, Sr_(1-x) Ba_(x) TiO₃ (0.001≦x≦0.300) or Sr_(1-x) Ca_(x) TiO₃ (0.001≦x≦0.300) as host material wherein the ratio of Sr/Ti is 1.05-0.95, 0.001-2.000 mol % of Y₂ O₃, 0.001-2.000 mol % of Co₂ O₃, and 0.001-1.000 mol % of CuO.
 2. A voltage-dependent non-linear resistance ceramic composition consisting essentially of:92.000-99.996 mol % of SrTiO₃, Sr_(1-x) Ba_(x) TiO₃ (0.001≦x≦0.300) or Sr_(1-x) Ca_(x) TiO₃ (0.001≦x≦0.300) as host material wherein the ratio of Sr/Ti is 1.05-0.95, 0.001-2.000 mol % of Y₂ O₃, 0.001-2.000 mol % of Co₂ O₃, 0.001-1.000 mol % of CuO, and 0.001-3.000 mol % of at least one metal oxide selected from the group consisting of Ag₂ O and Al₂ O₃.
 3. A voltage-dependent non-linear resistance ceramic composition consisting essentially of:95.00-99.997 mol % of Sr_(1-x) Ba_(x) TiO₃ (0.001≦x≦0.300) 0.001-2.000 mol % of Y₂ O₃, 0.001-2.000 mol % of Co₂ O₃, and 0.001-1.000 mol % of CuO.
 4. A voltage-dependent non-linear resistance ceramic composition consisting essentially of:92.000-99.996 mol % of Sr_(1-x) Ba_(x) TiO₃ (0.001≦x≦0.300), 0.001-2.000 mol % of Y₂ O₃, 0.001-2.000 mol % of Co₂ O₃, 0.001-1.000 mol % of CuO, and 0.001-3.000 mol % of at least one of Ag₂ O and Al₂ O₃.
 5. A voltage-dependent non-linear resistance ceramic composition consisting essentially of:95.000-99.997 mol % of Sr_(1-x) Ca_(x) TiO₃ (0.001≦x≦0.300), 0.001-2.000 mol % of Y₂ O₃, 0.001-2.000 mol % of Co₂ O₃, and 0.001-1.000 mol % of CuO.
 6. A voltage-dependent non-linear resistance ceramic composition according to claim 5 consisting of:95.000-99.997 mol % of Sr_(1-x) Ca_(x) TiO₃ (0.001≦x≦0.300), 0.001-2.000 mol % of Y₂ O₃, 0.001-2.000 mol % of Co₂ O₃, and 0.001-1.000 mol % of CuO.
 7. A voltage-dependent non-linear resistance ceramic composition consisting essentially of:92.000-99.996 mol % of Sr_(1-x) Ca_(x) TiO₃ (0.001≦x≦0.300), 0.001-2.000 mol % of Y₂ O₃, 0.001-2.000 mol % of Co₂ O₃, 0.001-1.000 mol % of CuO, and 0.001-3.000 mol % of at least one of Ag₂ O and Al₂ O₃.
 8. A voltage-dependent non-linear resistance ceramic composition according to claim 7 consisting of:92.000-99.996 mol % of Sr_(1-x) Ca_(x) TiO₃ (0.001≦x≦0.300), 0.001-2.000 mol % of Y₂ O₃, 0.001-2.000 mol % of Co₂ O₃, 0.001-1.000 mol % of CuO, and 0.001-3.000 mol % of at least one of Ag₂ O and Al₂ O₃.
 9. A voltage-dependent non-linear resistance ceramic composition consisting essentially of:93.000-99.995 mol % of SrTiO₃ having Sr/Ti ratio of 1.050-0.950, 0.001-2.000 mol % of Y₂ O₃, 0.001-2.000 mol % of Co₂ O₃, 0.001-1.000 mol % of CuO, and 0.001-1.000 mol % of one oxide selected from the group consisting of BaO, SiO₂, MgO and MnO₂.
 10. A voltage-dependent non-linear resistance ceramic composition according to claim 9 consisting of:93.000-99.995 mol % of SrTiO₃ having an Sr/Ti ratio of 1.050-0.950, 0.001-2.000 mol % of Y₂ O₃, 0.001-2.000 mol % of Co₂ O₃, 0.001-1.000 mol % of CuO, and 0.001-1.000 mol % of one oxide selected from the group consisting of BaO, SiO₂, MgO and MnO₂.
 11. A voltage-dependent non-linear resistance ceramic composition consisting essentially of:91.000-99.994 mol % of SrTiO₃ having Sr/Ti ratio of 1.050-0.950, 0.001-2.000 mol % of Y₂ O₃, 0.001-2.000 mol % of Co₂ O₃, 0.001-1.000 mol % of CuO, and 0.001-1.000 mol % of Ag₂ O, 0.001-1.000 mol % of one oxide selected from the group consisting of BaO, SiO₂, MgO and MnO₂, and 0.001-1.000 mol % of at least one oxide NiO, MoO₃, BeO, Fe₂ O₃, Li₂ O, Cr₂ O₃, PbO, CaO, TiO₂, P₂ O₅, Sb₂ O₃, Al₂ O₃ and V₂ O₅.
 12. A voltage-dependent non-linear resistance ceramic composition according to claim 11 consisting of:95.000-99.994 mol % of SrTiO₃ having an Sr/Ti ratio of 1.050-0.950, 0.001-2.000 mol % of Y₂ O₃
 0. 001-2.000 mol % of Co₂ O₃,0.001-1.000 mol % of CuO, 0.001-1.000 mol % of Ag₂ O, 0.001-1.000 mol % of one oxide selected from the group consisting of BaO, SiO₂, MgO and MnO₂, and 0.001-1.000 mol % of at least one oxide selected from the group consisting of NiO, MoO₃ BeO, Fe₂ O₃, Li₂ O, Cr₂ O₃, PbO, CaO, TiO₂, P₂ O₅, Sb₂ O₃, Al₂ O₃ and V₂ O₅. 